高等有机化学习题(2)
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高等有机化学习题(2)
Problem Ⅲ
1. Calculate △H θ for the reaction
CH 3
+Cl
F CH3Cl +
F
△
H θf (Cl-F) = - 51.1 KJmol -1
2. The following reaction was described as a first-order reaction .Suggest a reaction mechanism.
C 6H 5
C 6H 5
C
C NC
NC
CN
CN
+C 6H 5
6H 5
CN CN
CN CN
3. The following reaction was described as a second-order reaction. Suggest a reaction mechanism.
C 6H 5N NH
C 6H 6
N 2
+
4. Suggest a reaction mechanism for the reaction.
NH 2
2
NH 2
CH 3
Cl
CH 3
+
CH 3
5. The κH and κD of following reaction was determined.
(CH 3)2CHBr (CD 3)2CHBr
C 2H 5ONa
25℃
Alkene
κH ＝1.76 sec -1κD ＝0.26 sec -1
（1） Calculate the isotopic effect.
（2） Suggest a reaction mechanism.
6. Compare the each of the following pairs of reaction. Which reaction was more negative entropy of activation?
(1) A
+
COOH
COOH
COOH
COOH
B C CH 2
H 3C H 3C
2
C CHC(CH 3)3
H 3C
H 3C
(2) A CH 3I
+
NH 3
CH 3NH 3I
B
CH 3I
+
NH 2
CH 3NH 2
+
I
7. The base catalysis reaction of carbonyl compound includes two step ：
HA
+
B
A -
+
BH
A
-
HA
+
Product
κκ-1
2
Lead out the dynamic equation for general base catalysis (κ2 >>κ-1 ) and specific base catalysis (κ2 <<κ-1 ) respectively. ( reaction rate = d[product]/dt)
Problem Ⅳ
1. The pKas of m- and p-iodoxybenzoic acid in water at 25℃ are 3.50 and 3.44 respectively. Calculate σm and σp for the iodixy group (-IO 2).
2. Which is the series of σ constant for the reactions?
NH 2CH 3
+
H 2O
NHCH 3
+
H 3O
O 2N
O 2N
3. What is the sign of ρ for the reactions? (1) ArCH 2NMe 2+
MeI
ArCH 2NMe 3I
(2)
+
EtO ArSO 2OCH 3ArSO 3+
MeOEt
(3) +
EtI
ArONa
ArOEt
+
NaI
(4)
x
HNO 3
H 2SO 4
x
NO 2
(5) x
x
S
SH
+
H 2O
+
H 3O
4. The pKas of benzoic acid 、phenyl acetic acid and phenol are 4.20,4.31 and 9.98 respectively. Calculate pKas for the following compounds.
Cl O 2N
OH
COOH
Cl
CH 2COOH
(1)(2)
(3)